U.S. patent application number 16/640821 was filed with the patent office on 2021-02-11 for control device for vehicle and control method for vehicle.
This patent application is currently assigned to JATCO Ltd. The applicant listed for this patent is JATCO Ltd, NISSAN MOTOR CO., LTD.. Invention is credited to Takashi ENOMOTO, Masaharu MOCHIZULKI, Yoshimasa NISHIHIRO.
Application Number | 20210039625 16/640821 |
Document ID | / |
Family ID | 1000005209576 |
Filed Date | 2021-02-11 |
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United States Patent
Application |
20210039625 |
Kind Code |
A1 |
NISHIHIRO; Yoshimasa ; et
al. |
February 11, 2021 |
CONTROL DEVICE FOR VEHICLE AND CONTROL METHOD FOR VEHICLE
Abstract
A control device for a vehicle includes a drive shaft, an engine
coupled to the drive shaft, an electric motor coupled to the drive
shaft, and a control unit. The control unit increases a torque of
the electric motor when an accelerator pedal opening increases to
equal to or more than a predetermined degree of opening during
switching of driving sources, and decreases the torque of the
electric motor while increasing the torque of the engine after a
change of the torque of the engine turns to increase.
Inventors: |
NISHIHIRO; Yoshimasa;
(Zama-shi, Kanagawa, JP) ; MOCHIZULKI; Masaharu;
(Atsugi-shi, Kanagawa, JP) ; ENOMOTO; Takashi;
(Isehara-shi, Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JATCO Ltd
NISSAN MOTOR CO., LTD. |
Fuji-shi, Shizuoka
Yokohama-shi, Kanagawa |
|
JP
JP |
|
|
Assignee: |
JATCO Ltd
Fuji-shi, Shizuoka
JP
NISSAN MOTOR CO., LTD.
Yokohama-shi, Kanagawa
JP
|
Family ID: |
1000005209576 |
Appl. No.: |
16/640821 |
Filed: |
August 30, 2018 |
PCT Filed: |
August 30, 2018 |
PCT NO: |
PCT/JP2018/032182 |
371 Date: |
February 21, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60W 10/08 20130101;
B60W 2710/083 20130101; B60W 2710/0666 20130101; B60K 6/48
20130101; B60Y 2200/92 20130101; B60K 2006/4808 20130101; B60W
10/06 20130101; B60W 20/10 20130101; B60W 2540/103 20130101; B60W
2520/10 20130101 |
International
Class: |
B60W 20/10 20060101
B60W020/10; B60K 6/48 20060101 B60K006/48; B60W 10/06 20060101
B60W010/06; B60W 10/08 20060101 B60W010/08 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 30, 2017 |
JP |
2017-165381 |
Claims
1.-4. (canceled)
5. A control device for a vehicle, comprising: a drive shaft; an
engine coupled to the drive shaft; an electric motor coupled to the
drive shaft; and a controller configured to increase a torque of
the electric motor more than the torque of the electric motor
before an accelerator pedal opening increases to equal to or more
than a predetermined degree of opening when the accelerator pedal
opening increases to equal to or more than the predetermined degree
of opening during switching of driving sources in which the torque
of the electric motor is increased while a torque of the engine is
decreased, and decrease the torque of the electric motor while
increasing the torque of the engine after a change of the torque of
the engine turns to increase in association with the accelerator
pedal opening increasing to equal to or more than the predetermined
degree of opening.
6. The control device for the vehicle according to claim 5, wherein
the predetermined degree of opening has a different value depending
on a vehicle speed.
7. The control device for the vehicle according to claim 5, wherein
when an accelerator-on state is changed to an accelerator-off
state, the controller increases a load applied to the drive shaft
from the engine and the electric motor.
8. A control method for a vehicle, the vehicle including a drive
shaft, an engine coupled to the drive shaft, and an electric motor
coupled to the drive shaft, the control method comprising:
increasing a torque of the electric motor more than the torque of
the electric motor before an accelerator pedal opening increases to
equal to or more than a predetermined degree of opening when the
accelerator pedal opening increases to equal to or more than the
predetermined degree of opening during switching of driving sources
in which the torque of the electric motor is increased while a
torque of the engine is decreased, and decreasing the torque of the
electric motor while increasing the torque of the engine after a
change of the torque of the engine turns to increase in association
with the accelerator pedal opening increasing to equal to or more
than the predetermined degree of opening.
9. A control device for a vehicle, comprising: a drive shaft; an
engine coupled to the drive shaft; an electric motor coupled to the
drive shaft; means for increasing a torque of the electric motor
more than the torque of the electric motor before an accelerator
pedal opening increases to equal to or more than a predetermined
degree of opening when the accelerator pedal opening increases to
equal to or more than the predetermined degree of opening during
switching of driving sources in which the torque of the electric
motor is increased while a torque of the engine is decreased; and
means for decreasing the torque of the electric motor while
increasing the torque of the engine after a change of the torque of
the engine turns to increase in association with the accelerator
pedal opening increasing to equal to or more than the predetermined
degree of opening.
Description
TECHNICAL FIELD
[0001] The present invention relates to a control device and a
control method for a vehicle including an engine and an electric
motor as driving sources.
BACKGROUND ART
[0002] JP2008-273460A discloses that, in a vehicle including an
engine and a motor-generator as driving sources, the driving
sources are switched by executing a control that gradually
increases a torque of the motor-generator while gradually
decreasing a torque of the engine when transitioning from a
traveling mode (HEV mode) in which traveling is performed by both
the engine and the motor-generator to a traveling mode (EV mode) in
which traveling is performed by only the motor-generator.
SUMMARY OF INVENTION
[0003] According to a control disclosed in JP2008-273460A, a
generation of a shock in association with switching of the driving
sources can be suppressed when the traveling mode is transitioned
from the HEV mode to the EV mode. However, in the above-described
document, no measure is mentioned for the case where an accelerator
pedal is pressed during the switching of the driving sources, in
other words, while the torque of the engine is being decreased, and
a return to the HEV mode is necessary.
[0004] An object of the present invention is to secure a driving
response of a vehicle when an accelerator pedal is pressed during
switching of driving sources.
[0005] According to an aspect of the present invention, a control
device for a vehicle includes a drive shaft, an engine coupled to
the drive shaft and an electric motor coupled to the drive shaft.
The control device for the vehicle includes a control unit that
increases a torque of the electric motor when an accelerator pedal
opening increases to equal to or more than a predetermined degree
of opening during switching of driving sources in which the torque
of the electric motor is increased while a torque of the engine is
decreased, and decreases the torque of the electric motor while
increasing the torque of the engine after a change of the torque of
the engine turns to increase.
[0006] According to another aspect of the present invention, a
control method for a vehicle is provided. The vehicle includes a
drive shaft, an engine coupled to the drive shaft and an electric
motor coupled to the drive shaft. The control method for the
vehicle includes increasing a torque of the electric motor when an
accelerator pedal opening increases to equal to or more than a
predetermined degree of opening during switching of driving sources
in which the torque of the electric motor is increased while a
torque of the engine is decreased, and decreasing the torque of the
electric motor while increasing the torque of the engine after a
change of the torque of the engine turns to increase.
[0007] The above-described configuration ensures securing a driving
response of a vehicle while suppressing a generation of a shock
when an accelerator pedal is pressed due to, for example, a
change-of-mind of a driver during switching of driving sources.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a schematic diagram illustrating an overall
configuration of a vehicle drive system according to one embodiment
of the present invention.
[0009] FIG. 2 is a flowchart illustrating a basic procedure of a
driving source switching control (switching from engine traveling
to EV traveling) according to the embodiment.
[0010] FIG. 3 is a flowchart illustrating a content of a process
relating to returning to the engine traveling of the driving source
switching control.
[0011] FIG. 4 is an explanatory diagram illustrating a trend of an
operating range map according to the one embodiment of the present
invention.
[0012] FIG. 5 is an explanatory diagram illustrating an operation
of the vehicle drive system by the driving source switching control
according to the embodiment.
[0013] FIG. 6 is an explanatory diagram illustrating an operation
of a vehicle drive system according to a comparative example.
[0014] FIG. 7 is an explanatory diagram illustrating an operation
of the vehicle drive system when transitioned to an accelerator off
state.
DESCRIPTION OF EMBODIMENTS
[0015] The following describes embodiments of the present invention
with reference to the drawings.
[0016] (Configuration of Vehicle Drive System)
[0017] FIG. 1 schematically illustrates an overall configuration of
a vehicle drive system P according to one embodiment of the present
invention.
[0018] The vehicle drive system P includes an engine 1 and a
motor-generator 5 as driving sources. The engine 1 and the
motor-generator 5 are both coupled to right and left driving wheels
8. On a power transmission path coupling the engine 1 to the
driving wheels 8, an automatic transmission TM is interposed. The
motor-generator 5 is coupled to the driving wheels 8 via the
automatic transmission TM (specifically, a variator 4). While in
the embodiment, the engine 1 and the motor-generator 5 are coupled
in parallel to the variator 4 via independent power transmission
paths, the engine 1 and the motor-generator 5 may be disposed on an
identical power transmission path that extends from the variator
4.
[0019] The automatic transmission TM is a continuously variable
transmission, and includes a torque converter 2, a clutch 3, and
the variator 4 in an order from a side close to the engine 1 on the
power transmission path approaching the driving wheels 8. The
automatic transmission TM converts a rotative power input from the
engine 1 and the motor-generator 5 at a predetermined speed ratio,
and outputs to the driving wheels 8 via a differential gear 6.
[0020] The torque converter 2 includes a pump impeller 21 coupled
to an input shaft of the torque converter 2 and a turbine runner 22
coupled to an output shaft of the torque converter 2, and transmits
the input rotative power to the output shaft via a fluid dynamic
action. The torque converter 2 further includes a lock-up clutch 23
coupled to the output shaft, and directly couples the input shaft
to the output shaft of the torque converter 2 by bringing the
lock-up clutch 23 into an engaged state to ensure reducing a
transmission loss due to a fluid connection. An engagement and a
disengagement of the lock-up clutch 23 can be switched by
controlling a hydraulic pressure affecting the lock-up clutch
23.
[0021] The clutch 3 is disposed between the torque converter 2 and
the variator 4, and includes a friction engaging element
(hereinafter referred to as an "input element") 31 coupled to a
crankshaft (an output shaft of the torque converter 2 in this
embodiment) of the engine 1 and a friction engaging element
(hereinafter referred to as an "output element") 32 coupled to the
input shaft (specifically, a rotation shaft of a primary pulley 41)
of the variator 4. The clutch 3 engages and disengages the input
element 31 and the output element 32 to couple and cuts off the
engine 1 to/from the variator 4 and the driving wheels 8. The
operation of the clutch 3 is controlled by adjusting the hydraulic
pressure affecting the input element 31 or the output element
32.
[0022] The variator 4 includes the primary pulley 41 and a
secondary pulley 42 as variating elements, and includes a metal
belt 43 wound between this pair of pulleys 41 and 42. The variator
4 ensures steplessly changing a speed ratio by changing a ratio of
a contact diameter of the metal belt 43 on the primary pulley 41
and the secondary pulley 42. The speed ratio of the variator 4 is
controlled by adjusting the hydraulic pressure affecting movable
sheaves of the primary pulley 41 and the secondary pulley 42, and
changing widths of V-grooves formed between the movable sheaves and
fixed sheaves.
[0023] The motor-generator 5 can function as an electric generator
not only functioning as an electric motor. It is possible to employ
an electric motor operable only as the electric motor, instead of
the motor-generator 5. The motor-generator 5 includes a rotor 51
coupled to the output shaft and a stator 52 disposed in a
concentric manner with the rotor 51 in the peripheral area of the
rotor 51. By controlling a supply of the electric power to an
electromagnetic coil disposed in the stator 52, the motor-generator
5 can function as the electric motor to generate a torque. The
torque of the motor-generator 5 is transmitted to a rotation shaft
of the variator 4 (an input shaft and the rotation shaft of the
primary pulley 41 in this embodiment) via a power transmission
medium, such as a gear. The supply of the electric power to the
motor-generator 5 is controlled by a power control unit in which an
inverter 55 is incorporated. A direct current supplied from a
battery 9 is converted into a three-phase alternating current by
the inverter 55, and is supplied to the motor-generator 5.
Meanwhile, the alternating current generated by a regeneration
operation of the motor-generator 5 is converted into a direct
current by the inverter 55, and is supplied to the battery 9. The
battery 9 is rechargeable by the current supplied from the
motor-generator 5.
[0024] A rotative power after shifting that is output from the
automatic transmission TM is transmitted to a drive shaft 7 via a
gear train set to a predetermined gear ratio and the differential
gear 6 to rotate the driving wheels 8. Thus, in the embodiment,
while the engine 1 is coupled to the drive shaft 7 by the clutch 3
in a disengageable/engageable manner, the motor-generator 5 is
coupled to the drive shaft 7 without via the clutch 3. Not only
limited to the engine 1 and the drive shaft 7, but it is obvious
that the motor-generator 5 may be coupled to the drive shaft 7 by
interposing a clutch in a disengageable/engageable manner between
the motor-generator 5 and the drive shaft 7.
[0025] The embodiment includes the lock-up clutch 23 of the torque
converter 2, the input element 31 and the output element 32 of the
clutch 3, and a mechanical drive type oil pump 10 as a source of
generation of the hydraulic pressure affecting the variating
elements 41 and 42 of the variator 4. The oil pump 10 is driven by
a rotative power of the engine 1, increases the hydraulic oil
pressure, and supplies the hydraulic oil to each portion via a
hydraulic pressure control circuit 11. FIG. 1 illustrates hydraulic
pressure supply passages from the hydraulic pressure control
circuit 11 to each portion by dotted lines with arrow heads.
[0026] The embodiment includes an electrically operated type oil
pump 12 in addition to the oil pump 10. The oil pump 12 is actuated
by an electric power supplied from the battery 9, and increases the
hydraulic oil pressure. The hydraulic oil after being increased can
be supplied to each portion via the hydraulic pressure control
circuit 11 similarly to the case by the oil pump 10. The
electrically operated type oil pump 12 can, for example, control
the hydraulic pressure applied to the clutch 3 during a stop of the
engine 1.
[0027] (Configuration and Basic Operation of Control System)
[0028] Operations of the engine 1 and the motor-generator 5 are
controlled by a controller 101. It is also possible to configure as
a combination of an engine controller and a motor-generator
controller by distributing functions possessed by the controller
101 relating to the control of the engine 1 and the motor-generator
5 to a plurality of controllers. The controller 101 is configured
as an electronic control unit, and is formed of a central
processing unit (CPU), various kinds of storage devices, such as a
RAM and a ROM, and a microcomputer including, for example,
input/output interfaces.
[0029] The controller 101 is one that provides a function of a
"control unit" according to the embodiment, and a "control device
for a vehicle" according to the embodiment is configured by
including the drive shaft 7, the engine 1, and the motor-generator
5 besides the controller 101. While in the embodiment, the rotation
shaft (hereinafter, referred to as an "output shaft" in some cases)
7 coupled to the driving wheels 8 is supposed to be a "drive
shaft," the "drive shaft" is not limited to the output shaft 7, and
may be any shaft that can transmit the rotative power from the
engine 1 and the motor-generator 5 to the driving wheels 8, such as
a rotation shaft of the primary pulley 41 or a rotation shaft of
the secondary pulley 42. In this sense, the "control device for a
vehicle" can be configured by including the rotation shaft of the
primary pulley 41 or the like instead of the output shaft 7.
[0030] In the embodiment, a signal from an accelerator sensor 111
that detects an operation amount (hereinafter, referred to as an
"accelerator pedal opening") APO of the accelerator pedal by a
driver, and a signal from a vehicle speed sensor 112 that detects a
vehicle traveling speed (hereinafter, referred to as a "vehicle
speed") VSP are input to the controller 101 in relation to a
driving force control of the vehicle, as well as signals from
various kinds of sensors that detect, for example, a rotation speed
NE of the engine 1, a temperature TW of a cooling water of the
engine 1, a rotation speed Npri of the primary pulley 41, a
rotation speed Nsec of the secondary pulley 42, a pressure Ppri of
the hydraulic oil affecting the primary pulley 41, a pressure Psec
of the hydraulic oil affecting the secondary pulley 42, a
temperature Toil of the hydraulic oil of the automatic transmission
TM, and a position SFT of a shift lever, are input. In the
embodiment, the vehicle speed sensor 112 is disposed to be able to
measure a rotation speed of the drive shaft 7, and the controller
101 calculates the vehicle speed VSP on the basis of a signal from
the vehicle speed sensor 112.
[0031] The controller 101 determines a region to which a current
operating state of the vehicle belongs on the basis of the various
kinds of signals, such as the accelerator pedal opening APO and the
vehicle speed VSP, and switches the driving sources between the
engine 1 and the motor-generator 5 corresponding to its
determination result. Specifically, while the motor-generator 5
serves as the driving source in an operating range (hereinafter,
referred to as a "first region") R1 on a low load side with the
accelerator pedal opening APO being less than a predetermined
degree of opening APO1, the engine 1 serves as the driving source
in an operating range (hereinafter, referred to as a "second
region") R2 on a high load side with the accelerator pedal opening
APO being equal to or more than the predetermined degree of opening
APO1. Thus, in the embodiment, the driving source is alternatively
selected between the engine 1 and the motor-generator 5. However,
while only the motor-generator 5 serves as the driving source in
the first region R1, the engine 1 and the motor-generator 5 may be
used in combination as the driving source in the second region R2
to execute a torque assist by the motor-generator 5.
[0032] FIG. 4 illustrates an exemplary operating range map. The
operating range map is defined by the accelerator pedal opening APO
and the vehicle speed VSP, and, on the basis of the degree of
opening APO1 preliminarily determined corresponding to the vehicle
speed VSP, the region less than the predetermined degree of opening
APO1 (illustrated with diagonal lines) corresponds to the first
region R1 and the region equal to or more than the predetermined
degree of opening APO1 corresponds to the second region R2. While
in the embodiment, the predetermined degree of opening APO1 is set
to a different value depending on the vehicle speed VSP,
specifically, set to a small value as the vehicle speed VSP is in a
high region, it is also possible to set the predetermined degree of
opening APO1 to a constant value. The controller 101 compares the
current accelerator pedal opening APO with the predetermined degree
of opening APO1 on the basis of the vehicle speed VSP to determine
the regions R1 and R2 to which the operating states belong.
[0033] When the accelerator pedal opening APO is less than the
predetermined degree of opening APO1, and the motor-generator 5 is
selected as the driving source, the engine 1 is stopped and the
clutch 3 is disengaged. The traveling in such a state is referred
to as an "EV traveling." Meanwhile, when the accelerator pedal
opening APO is equal to or more than the predetermined degree of
opening APO1, and the engine 1 is selected as the driving source,
the supply of the electric power to the motor-generator 5 is
stopped and the clutch 3 is engaged to ensure the transmission of
the rotative power to the drive shaft 7 from the engine 1. The
traveling in such a state is referred to as an "engine
traveling."
[0034] When the accelerator pedal is returned from the state where
the accelerator pedal opening APO is equal to or more than the
predetermined degree of opening APO1, and the operating state is
transitioned from the second region R2 to the first region R1, to
switch the driving source from the engine 1 to the motor-generator
5, in other words, when switching from the engine traveling to the
EV traveling, the controller 101 executes a control to, while
gradually decreasing the torque of the engine 1, gradually increase
the torque of the motor-generator 5 corresponding to the decrease
of the engine torque. This suppresses the generation of the shock
in association with the switching of the driving sources. The
switching of the driving sources from the engine 1 to the
motor-generator 5 also occurs, not limited to when the accelerator
pedal opening APO is decreased due to returning of the accelerator
pedal by the driver so as to cross over a switching line (=APO1) to
a side of the first region R1, but even when a travelling
resistance is increased and the vehicle speed VSP is decreased,
such as when the vehicle approaches an uphill road from a flat
road, without no change in the position of the accelerator pedal
itself. FIG. 4 indicates an exemplary case of the switching caused
by the driver returning the accelerator pedal by arrows a1 and a2,
and an exemplary case of the switching caused by the increase of
the travelling resistance by an arrow a3.
[0035] Here, the case where, during the switching of the driving
sources, the accelerator pedal is pressed, and the accelerator
pedal opening APO is increased to equal to or more than the
predetermined degree of opening APO1 again is assumed. Such a
situation corresponds to, for example, when the driver who once
returns the accelerator pedal with the intention to decelerate has
a change-of-mind to reaccelerate, or when, after the vehicle
approaches the uphill road, the driver who feels the insufficient
vehicle speed presses the accelerator pedal with the intention to
accelerate.
[0036] In this case, the driving source is returned to the engine 1
in order to switch from the EV traveling to the engine traveling
again, and a fuel injection quantity to the engine 1 is increased
in order to ensure outputting the engine torque corresponding to
the accelerator pedal opening APO after the increase. However,
there exists a delay in the torque of the engine 1 until it
actually starts to be increased since a torque increase instruction
to the engine 1, in other words, since an increase instruction of
the fuel injection quantity. Therefore, only simply outputting the
torque increase instruction to the engine 1 in response to the
increase of the accelerator pedal opening APO causes a shortage in
the torque transmitted to the drive shaft 7 (hereinafter, referred
to as a "drive shaft torque").
[0037] Therefore, in the embodiment, in response to the increase of
the accelerator pedal opening APO during the switching of the
driving sources from the engine 1 to the motor-generator 5, a
control to increase the torque of the motor-generator 5 is executed
in conjunction with the torque increase instruction to the engine
1. This compensates the delay in the engine torque with the torque
of the motor-generator 5 to secure a driving response of the
vehicle. The control executed by the controller 101 regarding the
switching of the driving sources will be described with reference
to the following flowchart.
[0038] (Content of Driving Source Switching Control)
[0039] FIG. 2 illustrates a basic procedure of the driving source
switching control with a flowchart.
[0040] At S101, the signals indicative of the operating state of
the vehicle, such as the accelerator pedal opening APO and the
vehicle speed VSP, are read.
[0041] At S102, it is determined whether the condition is satisfied
for the transition from the engine traveling to the EV traveling or
not. Specifically, it is determined whether the operating state has
transitioned from the second region R2 where the accelerator pedal
opening APO is equal to or more than the predetermined degree of
opening APO1 to the first region R1 where the accelerator pedal
opening APO is less than the predetermined degree of opening APO1
or not. When the operating state is transitioned to the first
region R1, and the condition is satisfied for the transition from
the engine traveling to the EV traveling, the process proceeds to
S103, and when it is not in such a condition, the process returns
to S101 to repeatedly execute the process at S101 and 102.
[0042] At S103, the switching of the driving sources is started. In
the embodiment, the control to increase the torque of the
motor-generator 5 while decreasing the torque of the engine 1 is
executed, and, for example, while gradually decreasing the torque
of the engine 1, the torque of the motor-generator 5 is increased
corresponding to the decrease of the engine torque. The decrease of
the engine torque is, for example, caused by changing the fuel
injection quantity of the engine 1 at a decrease rate that ensures
the suppressed shock in association with the switching. The torque
of the motor-generator 5 is increased so as to compensate for the
shortage amount of the engine torque with respect to the drive
shaft torque corresponding to the accelerator pedal opening
APO.
[0043] At S104, it is determined whether the switching of the
driving sources from the engine 1 to the motor-generator 5 is
completed or not. For example, it is determined whether the fuel
injection quantity of the engine 1 is decreased down to a
preliminarily set fuel cut injection quantity or zero or not. When
the fuel injection quantity is sufficiently decreased, and the
switching of the driving sources is completed, the process proceeds
to S105, and when it is not yet completed, in other words, when the
fuel injection quantity is not decreased down to the fuel cut
injection quantity or zero, and it is during the switching of the
driving sources, the process proceeds to S107.
[0044] At S105, the clutch 3 is disengaged to cut off the
transmission of the rotative power to the drive shaft 7 from the
engine 1. That is, in the embodiment, after the accelerator pedal
opening APO is decreased to less than the predetermined degree of
opening APO1, and the operating state is transitioned to the first
region R1, the clutch 3 is not disengaged, and the engaged state is
maintained until the switching of the driving sources to the
motor-generator 5 is completed.
[0045] At S106, the supply of the fuel to the engine 1 is stopped
to stop the engine 1.
[0046] At S107, it is determined whether the accelerator pedal
opening APO is increased to equal to or more than the predetermined
degree of opening APO1 or not, in other words, after the operating
state is transitioned from the second region R2 on the high load
side to the first region R1 on the low load side, whether the
operating state is transitioned to the second region R2 again or
not. When the accelerator pedal opening APO is increased to equal
to or more than the predetermined degree of opening APO1, the
process proceeds to S201 illustrated in FIG. 3, and when the
accelerator pedal opening APO is not increased to equal to or more
than the predetermined degree of opening APO1, that is, when the
accelerator pedal opening APO still remains in less than the
predetermined degree of opening APO1, the process proceeds to
S108.
[0047] At S108, the switching of the driving sources is continued,
and the torque of the motor-generator 5 is increased while
decreasing the torque of the engine 1.
[0048] At S201, the torque increase instruction is output to the
engine 1 in order to switch the driving sources to the engine 1
again. Specifically, a target value of the engine torque that
ensures achieving the drive shaft torque corresponding to the
accelerator pedal opening APO after the increase is set, and the
fuel injection quantity of the engine 1 is increased on the basis
of this target engine torque.
[0049] At S202, the torque of the motor-generator 5 is controlled
to increase the torque of the motor-generator 5 so as to compensate
for the shortage amount of the actual engine torque with respect to
the target drive shaft torque. In the embodiment, this increases an
inclination of the torque change generated by the motor-generator 5
more than that before the transition of the operating range, in
other words, before the accelerator pedal opening APO is increased
to equal to or more than the predetermined degree of opening APO1.
While the actual engine torque may be detected by installing a
sensor at an appropriate rotating shaft, such as the input shaft of
the torque converter 2, it is also possible to detect by an
estimation calculation based on the current engine torque and the
target engine torque by approximating the delay of the actual
engine torque with respect to the target engine torque as a primary
delay.
[0050] At S203, it is determined whether the change of the torque
of the engine 1 is shifted to an increase or not. Whether the
torque of the engine 1 has reached a predetermined value or not
after being shifted to the increase may be determined, not only the
change of the engine torque being shifted to the increase. This
ensures obtaining an effect to compensate the shortage amount
caused by the delay of the engine torque with the torque of the
motor-generator 5 with more certainty.
[0051] At S204, decreasing the torque of the motor-generator 5 so
as to be in coordination with the increase of the engine torque
achieves the drive shaft torque corresponding to the accelerator
pedal opening APO, in other words, the drive shaft torque desired
by the driver.
[0052] At S205, matching of the torque of the engine 1 and the
drive shaft torque completes the switching of the driving sources
to the engine 1. This completes the transition to the engine
traveling, and the vehicle travels using the engine 1 as the
driving source. Thus, in the embodiment, the accelerator pedal
opening APO is increased to equal to or more than the predetermined
degree of opening APO1 during the switching of the driving sources,
and when the driving source is returned to the engine 1, the clutch
3 is maintained in the engaged state through the whole control from
the start of the driving source switching control (S103) to the
completion of the return to the engine 1 (S205).
[0053] In the embodiment, the functions of the "control unit" are
achieved by the processes at S102 to 104, S107, and S108 in the
flowchart illustrated in FIG. 2, and the processes at S201 to 204
in the flowchart illustrated in FIG. 3.
[0054] (Description of Operation by Timing Chart)
[0055] FIG. 5 schematically illustrates an operation of a vehicle
drive system P by the driving source switching control according to
the embodiment by a timing chart, and FIG. 6 illustrates the
operation by the comparative example. In both FIGS. 5 and 6, a
rotational speed NE and a torque TE of the engine 1 are indicated
by dotted lines, and a rotational speed NM and a torque TM of the
motor-generator 5 are indicated by solid lines. Furthermore, a
torque (input shaft torque) TSi applied to the input shaft of the
variator 4 is indicated by a two-dot chain line.
[0056] For ease of understanding the case of the embodiment (FIG.
5), first, the case of the comparative example (FIG. 6) will be
described, and next, the operation by the control according to the
embodiment will be described.
[0057] In FIG. 6, the control to switch the driving sources from
the engine 1 to the motor-generator 5 is executed in order to
transition from the engine traveling to the EV traveling when the
accelerator pedal is returned from a state where the operating
state is in a medium load region (APO APO1) to be transitioned to
the low load region (the first region R1) where the accelerator
pedal opening APO is less than the predetermined degree of opening
APO1 (time t1). The controller 101 outputs an instruction to
decrease the fuel injection quantity to the engine 1. In
conjunction with this, the controller 101 increases the torque of
the motor-generator 5 corresponding to the decrease of the engine
torque (time t2) to suppress the generation of the shock in
association with the switching of the driving sources. When the
fuel injection quantity is decreased to the fuel cut injection
quantity or zero, the supply of the fuel to the engine 1 is stopped
to complete the switching of the driving sources to the
motor-generator 5 and the transition to the EV traveling. Here,
during the switching of the driving sources, specifically, during
the torque of the engine 1 is decreased, in the case where the
accelerator pedal is pressed due to, for example, a change-of-mind
of the driver, and the accelerator pedal opening APO is increased
to be equal to or more than the predetermined degree of opening
APO1 again (time t3), it is necessary to return the driving source
to the engine 1 in order to allow the drive shaft torque TSd
corresponding to the accelerator pedal opening APO after the
increase to be achieved. In the comparative example, while the
torque increase instruction is output to the engine 1, the supply
of the electric power to the motor-generator 5 is stopped to
sharply decrease the torque of the motor-generator 5. Since the
torque increase instruction to the engine 1 until the engine torque
actually starts to be increased (time t4), there is a delay
corresponding to the operation property of the engine 1. Therefore,
in the drive shaft torque TSd, there is generated a shortage for an
amount corresponding to the delay of the engine torque. In FIG. 6,
the shortage amount of the drive shaft torque TSd caused by the
delay of the engine torque is indicated by the diagonal line.
[0058] Now, the operation by the control according to the
embodiment will be described. In FIG. 5, the operation from time t1
where the accelerator pedal is returned to transition the operating
state to the first region R1 on the low load side to time t3 where
the accelerator pedal is pressed by, for example, a change-of-mind
of the driver during the switching of the driving sources to
increase the accelerator pedal opening APO to equal to or more than
the predetermined degree of opening APO1 again is similar to that
of the comparative example.
[0059] In the case of the embodiment, while the torque increase
instruction is output to the engine 1 in response to the increase
of the accelerator pedal opening APO, a torque TM of the
motor-generator 5 is increased more than that when the accelerator
pedal opening APO is increased (time t3), and afterwards, the
torque TM of the motor-generator 5 is decreased when the change of
an actual engine torque TE is shifted to the increase (time t4).
Specifically, in order to allow the drive shaft torque TSd
corresponding to the accelerator pedal opening APO after the
increase to be achieved, the torque corresponding to the actual
shortage amount of the engine torque with respect to the target
value of the drive shaft torque TSd is generated by the
motor-generator 5. This compensates the shortage amount of the
drive shaft torque TSd caused by the delay after the torque
increase instruction until the engine torque TE actually starts to
be increased with the torque TM of the motor-generator 5, and
ensures securing the driving response of the vehicle in response to
the increase of the accelerator pedal opening APO. FIG. 5
illustrates a state where the inclination in the change of the
torque TM of the motor-generator 5 is increased more than that
before the increase of the accelerator pedal opening APO in
response to the increase of the accelerator pedal opening APO, and
furthermore, the change of the torque TM of the motor-generator 5
is also shifted to the decrease from the increase at time t4 where
the change of the actual engine torque TE is shifted to the
increase from the decrease. At time t5 where the torque TM of the
motor-generator 5 is decreased to zero, the torque TE of the engine
1 and the drive shaft torque TSd match to complete the switching of
the driving sources to the engine 1. Afterwards, the traveling is
performed with the engine 1 as the driving source.
[0060] FIG. 7 illustrates a case where the accelerator pedal is
returned to a state of accelerator off (APO=0) from the state where
the operating state is in the medium load region (APO.gtoreq.APO1)
(time t11), and the supply of the fuel to the engine 1 is stopped.
In this case, the switching of the driving sources is not
performed, and the engine 1 continuously serves as the driving
source. However, in this embodiment, maintaining the clutch 3 in
the engaged state and operating the motor-generator 5 as the
electric generator increase the load applied to the drive shaft 7
from the engine 1 and the motor-generator 5. When the accelerator
pedal is pressed and the accelerator pedal opening APO is increased
(time t31), the regeneration operation of the motor-generator 5 is
stopped and the supply of the fuel to the engine 1 is resumed.
[0061] (Description of Operational Advantage)
[0062] The control device for the vehicle according to the
embodiment is configured as described above. The following
describes the effects obtained by the embodiment.
[0063] First, during the switching of the driving sources, in the
embodiment, when the accelerator pedal opening APO is increased to
equal to or more than the predetermined degree of opening APO1
during the switching of the driving sources from the engine 1 to
the motor-generator 5, in other words, when the switching line
(=APO1) is crossed over toward the second region R2 on the high
load side due to the increase of the accelerator pedal opening APO
after the operating state is transitioned to the first region R1 on
the low load side in the operating range map illustrated in FIG. 4,
increasing the torque TM of the motor-generator 5 compensates the
delay of the engine torque TE after the torque increase instruction
until the torque TE of the engine 1 actually starts to be increased
to ensure suppressed generation of the shortage in the drive shaft
torque TSd. After the change of the engine torque TE is shifted to
the increase, decreasing the torque TM of the motor-generator 5
while increasing the torque TE of the engine ensures achieving the
target drive shaft torque TSd while suppressing the generation of
the shock caused by the rapid decrease of the torque TM of the
motor-generator 5. Thus, with the embodiment, when the accelerator
pedal is pressed due to, for example, a change-of-mind of the
driver during the switching of the driving sources, the driving
sources are appropriately controlled to ensure securing the driving
response of the vehicle while suppressing the generation of the
shock.
[0064] Second, setting the accelerator pedal opening (predetermined
degree of opening APO1) that determines the switching line of the
driving sources to a different value depending on the vehicle speed
VSP ensures utilizing the operation properties of both the engine 1
and the motor-generator 5 to contribute to establish the efficient
vehicle drive system P.
[0065] Third, when the accelerator pedal is completely returned
from the state where the operating state is in the second region R2
to be in the state of accelerator off (APO=0), continuously using
the engine 1 as the driving source and maintaining the clutch 3 in
the engaged state ensure utilizing the engine brake and ensure
securing the response at reacceleration. Furthermore, causing the
motor-generator 5 to operate as the electric generator, and
recharging the electric power generated by the electric generation
to the battery 9 ensure improved efficiency of the whole vehicle
drive system P.
[0066] The concepts extracted from the above description other than
those described in claims are brought together below.
[0067] First, it is a control device for a vehicle. The vehicle
includes a drive shaft, an engine coupled to the drive shaft, and
an electric motor coupled to the drive shaft. The control device
for the vehicle includes a control unit that, when an accelerator
pedal opening is increased to be equal to or more than a
predetermined degree of opening during switching of driving sources
which decreases a torque of the engine gradually and increases a
torque of the electric motor corresponding to a decrease of the
engine torque, gives an instruction to increase a torque to the
engine, and increases a changing rate of a torque of the electric
motor more than the changing rate of the torque of the electric
motor before the accelerator pedal opening is increased to equal to
or more than the predetermined degree of opening.
[0068] Second, it is the control device for the vehicle in which,
after the accelerator pedal opening is increased to equal to or
more than the predetermined degree of opening, the control unit
sets a target torque of the engine corresponding to the accelerator
pedal opening after the increase, and decreases the torque of the
electric motor while increasing the torque of the engine toward the
target torque.
[0069] Third, it is the control device for the vehicle in which the
predetermined degree of opening has a different value depending on
a vehicle speed.
[0070] Fourth, it is the control device for the vehicle in which
the control unit has a second region where the accelerator pedal
opening is equal to or more than the predetermined degree of
opening as an operating range where a traveling is performed by the
engine, and a first region where the accelerator pedal opening is
less than the predetermined degree of opening (excluding
accelerator off state) as an operating range where a traveling is
performed by the electric motor. The control unit executes the
switching of the driving sources when the operating state is
transitioned from the second region to the first region.
[0071] Fifth, it is the control device for the vehicle in which the
control unit increases a load applied to the drive shaft from the
engine and the electric motor when an accelerator-on state is
changed to an accelerator-off state.
[0072] While the embodiment of the present invention has been
described above, the present invention is not limited to this, and
it is needless to mention that various changes and modifications
can be made within a range of the matter disclosed in the
claims.
[0073] The present application claims a priority of Japanese Patent
Application No. 2017-165381 filed with the Japan Patent Office on
Aug. 30, 2017, all the contents of which are hereby incorporated by
reference.
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